1. Field of the Invention
The present invention relates to a holding jig, and a measurement device and a holding device using the jig. More particularly, it relates to a holding jig which can hold even a brittle holding target without damaging the target, and a measurement device which can measure the through channel characteristics of a fluid in a through channel of the holding target held by using the holding jig, while acquiring the air tightness of the holding target having therein the through channel for the fluid. Further particularly, it relates to a measurement device which can stably and simply measure the pressure loss of a filter.
2. Description of the Related Art
Heretofore, there has been a demand for the automation of processes such as a manufacturing process, an inspection process and a shipping process to manufacture highly brittle products having three-dimensional shapes, for example, a glass product, a ceramic product, a ceramic structure, a ceramic honeycomb structure and the like in large amounts and at a low cost along a manufacturing line of the products. In, for example, Japanese Patent Laid-Open No. 7-266278, there is disclosed an air bag which holds a insulator in a holding method of the insulator.
However, it has been difficult to fully automate holding means necessary for automating the processing, conveyance, measurement and the like of these highly brittle products having the three-dimensional shapes, because manpower is often required in the middle of each process along an automation line owing to the brittleness of the products. Moreover, the automated holding means requires not only an expensive control system but also much cost for the adjustment, operation and maintenance of the control system. Furthermore, there has been a limit to the speed of the automation line to prevent falling-down and damage due to added shock during the conveyance, processing, inspection and shipping.
As a catalyst carrier for purifying an exhaust gas discharged from an engine, a honeycomb structure is broadly used in which a plurality of cells provided side by side to connect two end faces to each other are formed by a plurality of partition walls. Moreover, as a filter for collecting and removing a particulate material included in a fluid such as the exhaust gas discharged from a diesel engine, a diesel particulate filter (DPF) is broadly used. The DPF includes the porous partition walls of the honeycomb structure provided with a large number of pores (communication pores), and the inflow end faces of the predetermined cells and the outflow end faces of the remaining cells are alternately plugged. The exhaust gas including the particulate material, which has flowed into the cells from the side of the inflow end faces thereof, flows out from the side of the outflow end faces through the partition walls which function as filter layers. At this time, the particulate material is collected on the porous partition walls.
Such a honeycomb structure or DPF (hereinafter referred to as the honeycomb structure in all) is usually installed and used along a passage for the exhaust gas discharged from the engine, but physical characteristics of the honeycomb structure have not a little influence on the performance of the engine, and hence it is necessary to beforehand measure various physical characteristics. Especially, it is necessary to beforehand measure a pressure loss at an arbitrary constant flow speed, as a part of the specifications of the honeycomb structure.
Heretofore, the measurement of the pressure loss of the honeycomb structure has usually been performed by providing the honeycomb structure as the target of the measurement of the pressure loss along a predetermined passage for the fluid and passing the fluid through the structure at a predetermined flow speed by fluid passing means such as a blower to measure the differential pressure of the fluid generated in this case (see, e.g., Japanese Patent No. 2807370).
Moreover, Japanese Patent Laid-Open No. 2005-172652 discloses a pressure loss measurement device of the honeycomb structure, and honeycomb structure retaining means (holding means) is used in this pressure loss measurement device. This honeycomb structure holding means used in the pressure loss measurement device of the honeycomb structure includes one or more elastic seal members constituted of a first holding means element which holds the inflow end face side of the filter and a second holding means element which holds the outflow end face side of the honeycomb structure, and at least a part of the first and second holding means elements is formed into a tubular shape having a hollow portion, and the seal members are provided in a ring shape. The holding means also includes a frame member provided outside the elastic seal member. The end of the honeycomb structure including the inflow end face and/or the outflow end face is inserted into the elastic seal member, and a gas or a liquid is introduced into the hollow portion of the elastic seal member to expand the elastic seal member, whereby the outer peripheral surface of the honeycomb structure and the elastic seal member, the frame member and the elastic seal member, or the elastic seal members can come in contact closely with each other to hold the honeycomb structure.
Moreover, the honeycomb structure holding means described in Japanese Patent Laid-Open No. 2005-172652 acquires air tightness in the honeycomb structure on the sides of the inflow end face and outflow end face of the honeycomb structure by the tubular elastic seal member. At this time, when the whole shape of the honeycomb structure as the holding target is columnar, that is, when the sectional shape thereof is round, the honeycomb structure can be held while acquiring sufficient air tightness.
Moreover, in recent years, with the tightening of environmental standards, the honeycomb structure has been lightened and space-saved, and hence there is a rising demand for the honeycomb structure having a sectional shape other than a round shape. As to the honeycomb structure holding means described in Japanese Patent Laid-Open No. 2005-172652, when the honeycomb structure having such a shape is the holding target, the tubular elastic seal member is deformed in accordance with the shape of the holding target, and a gap is made between the member and a portion of the sectional shape of the holding target in which a curvature radius partially decreases, whereby the deformed member cannot keep the air tightness.
Furthermore, as the above honeycomb structure having the sectional shape other than the round shape, a ceramic honeycomb structure is often integrally formed when manufactured. However, the dimensional precision of the outer diameter of the cross section of the integrally formed honeycomb structure is often poor as compared with the honeycomb structure having an outer periphery thereof coated. Also in this case, the holding means described in Japanese Patent Laid-Open No. 2005-172652 has poor air tightness, and it is difficult to obtain the precise and stable pressure loss.